The invention relates to a sprocket cover arrangement for a hand-held chain saw comprising a sprocket cover, a housing, at least one stud bolt attached to the housing for screw-connecting the sprocket cover to the housing, and a nut to be screwed onto a free threaded end of the stud bolt that passes in the mounted state of the sprocket cover through an opening of the sprocket cover.
Hand-held chain saws have a saw chain that circulates externally on a guide bar. For driving the saw chain, a sprocket with external teeth is provided and is driven by a drive motor. The external teeth of the sprocket engage the space between the members of the saw chain and drive the saw chain.
The drive shaft of the sprocket is supported in a housing of the chain saw. A sprocket cover is screwed to the housing and covers the area in which the sprocket is arranged. At least one stud bolt is attached to the housing for realizing the screw connection; in the mounted state of the sprocket cover, the stud bolt projects through an opening of the sprocket cover. A nut is screwed onto a free threaded end of this stud bolt and presses the sprocket cover against the housing.
The guide bar of the saw chain is threaded onto the at least one stud bolt and secured by being clamping between the housing and the sprocket cover. The sprocket cover, in addition to its protective function, also has a securing function for the guide bar. For maintenance work on the guide bar or for changing the guide bar, the sprocket cover is removed and the guide bar can be taken off or exchanged. During assembly, first the guide bar is threaded onto the at least one stud bolt and, subsequently, the sprocket cover is positioned in such a way that the at least one stud bolt projects through the opening of the sprocket cover. At the end of assembly, the nut is threaded onto the free threaded end of the stud bolt and tightened.
Assembling the arrangement is particularly difficult for the user at the location of use of the chain saw. The guide bar and sprocket cover must be held simultaneously in the mounting position while the nut must be screwed onto the stud bolt. The nut can drop to the ground and can be lost. In particular, in the case of an arrangement with two stud bolts, the weight of the not yet finally fixed guide bar can lead to canting of the screw connection.